The present invention relates to catheters for percutaneous transluminal use. More particularly, the present invention relates to low profile catheter shaft designs for use with catheters intended for accessing remote or tortuous vascular locations.
A wide variety of interventional procedures have been developed which require access to remote parts of the vascular system. One increasingly utilized coronary revascularization procedure, for example, is percutaneous transluminal coronary angioplasty (PTCA). In a typical PTCA procedure, a guiding catheter having a prebent distal tip is percutaneously introduced at a remote location such as the femoral artery using a conventional Seldinger technique. The guide catheter is advanced retrograde until it reaches the ascending aorta with the distal tip seated in the ostium of a desired coronary artery. Steering is accomplished during transluminal advancement by torquing the proximal end of the guide catheter as needed until the distal tip is positioned in the ostium.
An elongate, flexible guidewire is then advanced through and out the distal end of the guide catheter, and negotiated through the tortuous vasculature of the coronary arteries until it crosses a lesion to be dilated. A dilatation catheter is thereafter advanced along the guidewire until the dilatation balloon is positioned within the lesion.
Once properly positioned, the balloon is inflated one or more times to an inflation pressure on the order of six to twelve atmospheres or higher to dilate the lesion. Balloon catheters sized for the coronary arteries may inflate to a diameter in the range of from about two to about four cm. Following dilatation, the balloon is deflated and the catheter is proximally withdrawn from the patient.
Considerable effort has been devoted to reducing the profile and improving the trackability (flexibility) of PTCA and other interventional catheters. Improvements of this nature can enable the catheter to reach more remote and smaller treatment sites. These capabilities can permit treatment of both more remote coronary arteries as well as other narrow and tortuous vessels such as within the intracranial vasculature.
A further requirement of a successful dilatation or other therapeutic or diagnostic catheter is that the catheter shaft exhibit sufficient pushability. Pushability relates to the longitudinal transmission of force along the axial length of the catheter from the proximal end to the distal end. This characteristic is necessary to enable the physician to advance the catheter against resistive forces such as due to the tortuous path and small diameter of the vessel and target stenosis.
Notwithstanding the significant research effort in this technology, there remains a need for a catheter shaft design which minimizes the crossing profile and yet retains sufficient columns strength and torquability for the intended clinical objective. Preferably, the catheter shaft design can be adapted for any of a variety of functional applications, such as balloon dilatation and or drug or stint delivery catheters, either in an over the wire or a rapid exchange configuration.